1. Field of the Invention
This invention relates in general to semiconductor lasers and, more particularly, to semiconductor ridge waveguide lasers.
2. Description of Related Art
Early semiconductor lasers were fabricated from a single material, for example gallium arsenide (GaAs), which was appropriately doped to form a pn junction. When a forward current flows through the pn junction of a semiconductor laser device, stimulated emission occurs due to recombination of electron-hole pairs which causes coherent photons to be emitted. More particularly, coherent photons are emitted from a resonant cavity formed by polishing the ends of the semiconductor laser device.
In more modern heterostructure injection semiconductor lasers, the charge carriers are vertically injected through the barrier layers. Barrier materials are also used as a cladding layer to optically confine the stimulated emission occurring at the pn junction within the semiconductor. Unfortunately, in such vertical injections lasers the optimization of electrical properties compromises the optimization of optical properties and vice versa.